Fujitsu F2MC-16LX MB90580 Series Hardware Manual page 192

13.4 IEBus Communication Protocol
(3) Read lock address (control bits: 4H, 5H)
When the lock address is read (control bits: 4H, 5H), the address (12-bit) of the master that has issued the
lock instruction is configured in 1-byte units as shown below and is read.
Control bits: 4H
Control bits: 5H
(4) Locking and unlocking
The lock function is used to transmit a message over two or more communication frames. The unit that has
been locked cannot receive data from any unit other than the one that has locked it.
A unit is locked or unlocked as follows:
• Locking
When the lock command has been executed (control bits: 3H, AH, BH) and the acknowledge bit '0' in
the telegraph length field has been transmitted or received, but the number of data bytes specified by
the telegraph length bits cannot be transmitted or received successfully within the communication
frame, then the slave is locked by the master, and the bit related to locking (bit 2) in the slave status is
set.
• Unlocking
When the lock command (control bits: 3H, AH, BH) or unlock command (control bits: 6H) has been exe-
cuted, and the number of data bytes specified by the telegraph length bits can be transmitted or
received successful within one communication frame, then the slave is unlocked by the master and the
bit related to locking (bit 2) in the slave status is cleared.
Furthermore, the slave is not locked or unlocked while multiaddress communication is performed.
172 Chapter 13: IE Bus
Lower 8 bits
Undefined
MSB
Higher 4 bits
LSB
MB90580 Series